1 #define S_SIZE (1024 - (sizeof(unsigned int) + 1))
2
3 struct sbuff {
4 unsigned int count;
5 char buf[S_SIZE + 1];
6 };
7 static struct sbuff emergency, *emergency_ptr = &emergency;
8
sb_add(struct sbuff * m,const char * f,...)9 static int sb_add(struct sbuff *m, const char *f, ...)
10 {
11 va_list args;
12 int len;
13
14 if (likely(m->count < S_SIZE)) {
15 va_start(args, f);
16 len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
17 va_end(args);
18 if (likely(m->count + len < S_SIZE)) {
19 m->count += len;
20 return 0;
21 }
22 }
23 m->count = S_SIZE;
24 printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
25 return -1;
26 }
27
sb_open(void)28 static struct sbuff *sb_open(void)
29 {
30 struct sbuff *m = kmalloc(sizeof(*m), GFP_ATOMIC);
31
32 if (unlikely(!m)) {
33 local_bh_disable();
34 do {
35 m = xchg(&emergency_ptr, NULL);
36 } while (!m);
37 }
38 m->count = 0;
39 return m;
40 }
41
sb_close(struct sbuff * m)42 static void sb_close(struct sbuff *m)
43 {
44 m->buf[m->count] = 0;
45 printk("%s\n", m->buf);
46
47 if (likely(m != &emergency))
48 kfree(m);
49 else {
50 xchg(&emergency_ptr, m);
51 local_bh_enable();
52 }
53 }
54
55